With the advent of laparoscopic and endoscopic surgery, surgical patients are benefiting from shorter hospitalization, less pain, and generally better outcomes. However, the minimization of the size of incision a surgeon uses in these procedures has created some unique challenges.
Large tissue masses, such as fibroid tissue masses, are traditionally excised during a surgical procedure and removed intact from the patient through the surgical incision. These tissue masses can easily be 3 centimeters in diameter or larger. In minimally invasive surgery, the surgery is typically conducted using incisions of less than 1 centimeter, and often 5 millimeters or less. Thus, the trend toward the use of minimally invasive surgery has created a need to reduce large tissue masses to a size small enough to fit through an opening which may be 1 centimeter or smaller in size. One common procedure for reducing the size of large tissue masses is generally referred to as morcellation.
A surgeon performing a minimally invasive surgical procedure, such as, for example, a laparoscopic cholecystectomy, will often make three small incisions in the patients abdominal wall. A medial incision may be used for insertion of a video system, and two lateral incisions may be used for surgical instrumentation. If the incisions are small (e.g. 5 mm trocar ports), and the gallbladder contains stones larger than 5 mm in diameter, the stones may be morcellated and removed through a trocar inserted in one of the lateral incisions. Morcellation is facilitated by placing a specimen bag into the abdominal cavity and opening the specimen bag to facilitate access to the interior of the specimen bag. Specimen bags which are used for morcellation may also be referred to as containment bags or morcellation bags. Drawstrings for the specimen bag opening may be either inside the abdominal cavity, or alternatively, a portion of the strings may extend through the trocar outside the patient's abdominal wall.
In a laparoscopic cholecystectomy the entire gallbladder, containing stones and bile, is excised and inserted into the specimen bag. The bag opening may now be closed by pulling the drawstrings. The surgeon may continue to pull the drawstrings out of the trocar port, bringing a portion of the specimen bag to the outside of the patients abdominal wall, and leaving a portion of the specimen bag with the gallbladder and contents inside the patients abdominal cavity. The tissue in the bag may then be morcellated to facilitate removal of the bag and its contents through the trocar port.
Specially designed medical instruments, which are generally referred to as morcellators, have been developed to reduce the volume of excised tissue before it is removed from the patient. See, for example, the instruments described in U.S. Pat Nos. 5,037,379; 5,403,276; 5,520,634; 5,327,896 and 5,443,472. As those references illustrate, excised tissue is morcellated (i.e. debulked), collected and removed from the patient's body through, for example, a surgical trocar or directly through one of the surgical incisions.
Mechanical morcellators cut tissue using, for example, sharp end-effectors such as rotating blades. Electrosurgical and ultrasonic morcellators use energy to morcellate tissue. For example, a system for fragmenting tissue utilizing an ultrasonic surgical instrument is described in "Physics of Ultrasonic Surgery Using Tissue Fragmentation", 1995 IEEE Ultrasonics Symposium Proceedings, pages 1597-1600.
In order to prevent morcellated tissue from spreading to other parts of the body during and after the morcellation procedure, the excised tissue is, in most cases, placed in a specimen bag prior to being morcellated. However some morcellators are used without specimen bags. Specimen bags are, therefore, designed to hold excised tissue without spilling tissue, or tissue components, into the abdominal cavity during morcellation. It will be apparent that specimen bags used with morcellators must be strong enough to prevent tears or cuts which might spill the contents of the specimen bag.
Ultrasonic morcellation instruments may be particularly advantageous for use in certain surgical procedures and for debulking certain types of tissue. When using any morcellator it is important to ensure that the end effector of the morcellator does not penetrate the specimen bag. This concern is particularly applicable to ultrasonic morcellation instruments where the tip of the debulking end effector may have an excursion of between 50 and 300 micrometers, which would correspond to tip peak velocities ranging from 8.7 meters per second to 52.3 meters per second at 55,500 Hertz.
Thus, in an ultrasonic morcellator, there is potential for the tip of the end effector to penetrate the wall of conventional specimen bags. An ultrasonic surgical instrument tip vibrating at approximately 55,500 cycles per second may create a significant potential for fatigue and abrasion of the interior wall of conventional specimen bags, weakening the bag and making it susceptible to tearing as it is pulled out through the trocar.
A blunt or rounded ultrasonic morcellator tip reduces the possibility of unintended cutting or tearing of the specimen bag while the ultrasonic energy morcellates the tissue. U.S. Pat. No. 5,449,370, hereby incorporated herein by reference, describes a blunt tipped ultrasonic surgical instrument capable of morcellating tissue contained within a specimen bag (FIGS. 1-3, and text from Col. 3, line 44 to Col. 6, line 8 of U.S. Pat. No. 5,449,370). However, current specimen bags may be weakened or punctured when using an ultrasonic surgical instrument such as the one described in U.S. Pat. No. 5,449,370.
It would, therefore, be advantageous to provide a method of morcellation which is particularly adapted for use with an ultrasonic morcellation instrument. More particularly, it would be advantageous to provide a method of morcellation using a specimen bag with unique properties which make the bag substantially impervious to the end effector of an ultrasonic morcellation instrument. Further, it would be advantageous to provide a method of morcellation utilizing a specimen bag which is strong enough to withstand the impact and abrasion of an ultrasonic end-effector while remaining substantially impervious to fluids.